Shade netting and reflective mulches effect on yield and quality variables of ‘Gala Baigent’ and ‘Fuji Raku Raku’ apples

ABSTRACT Sunburn is possibly the main problem affecting the apple production in the Southern Hemisphere including Chile. This study focused on determining the effect of shade nets to reduce sunburn incidence and reflective mulch to improve colour on canopy microclimate, vegetative growth, fruit quality, return bloom and profitability of two apple cultivars (‘Gala Baigent’ and ‘Fuji Raku Raku’) in southern Chile. The treatments evaluated were net, mulch, net + mulch. Trees without net or mulch served as the control. Results showed that PAR transmitted under the netting was reduced in an average of 26% and the mulch increased the reflected PAR from 3% to 5% (grass row control) to 20%–37%. Shoot length, yield, fruit maturity and return bloom were not affected using either net or mulch. The incidence of sunburn under net was reduced by 76%–80%, compared to the control; however, it also reduced fruit colouration, especially in ‘Fuji Raku Raku’. The use of mulch under shade net increased the amount in 27% and 9% (average of seasons) of fruit in the Premium category of colour for ‘Gala Baigent’ and ‘Fuji Raku Raku’, respectively, which is only economically justified in circumstances of high incidence of sunburn and limitations of fruit colour.